Fish

Sturgeon

Acipenseridae · also called sturgeons

Critically Endangered ↓ carnivore Rivers & wetlands Coasts & shorelines Ocean

A sturgeon is a fish out of deep time. Its body plan — a cartilage skeleton, a shark-like tail, rows of bony plates instead of scales, a mouth that shoots out from under a long snout — was already old when the dinosaurs were young, and it has barely changed in 200 million years. That same slow, conservative biology is now the reason sturgeons are the most endangered large group of animals on the planet.

Overview

Sturgeons are the family Acipenseridae, about 26 species with the paddlefishes, in the large rivers, lakes, and coastal seas of the Northern Hemisphere. They are bottom-feeding carnivores that detect prey with four barbels under the snout and vacuum it up through a toothless, protrusible tube of a mouth. Many migrate between fresh and salt water to spawn.

Giants that keep an ancient body

The beluga sturgeon has historical records over 7 m and 1,500 kg, and the white sturgeon of the Pacific coast exceeds 6 m — among the largest freshwater fish alive. All keep a mostly cartilaginous skeleton, an upturned tail, a spiral-valve gut, and five rows of scutes.

Painfully slow to breed

Sturgeons mature very late — a beluga female not until 15 to 20 years, a lake sturgeon sometimes not until 25 — and then spawn only once every two to seven years. Individuals can live 60 to over 100 years. The unfertilised eggs of wild sturgeon are the original caviar, and their value drove a century of overfishing and, after the 1990s, mass poaching on the Caspian.

Status

Sturgeons are assessed as Critically Endangered as a family — around two thirds of species are Critically Endangered and most of the rest Endangered — after wild populations fell 90 per cent or more from overfishing, poaching, and dams that block the spawning rivers. Several, including the Chinese sturgeon, may already be functionally extinct in the wild, surviving only through hatchery stocking.

Sturgeon: common questions

Why are sturgeon called living fossils?

Because the group has kept a suite of primitive features and a body plan that is clearly recognisable in fossils more than 200 million years old, from a time before most modern fish groups existed. A sturgeon has a skeleton made largely of cartilage rather than bone, an asymmetrical, upturned tail like a shark's, a gut with a spiral valve rather than a simple tube, a mouth that shoots out from under the snout, and five rows of bony plates instead of scales. These are ancient characteristics, and while sturgeons are not literally unchanged, they have evolved slowly and conservatively, so a modern sturgeon is a reasonable window onto what some early ray-finned fish were like.

How does a sturgeon find and eat its food?

A sturgeon feeds along the bottom, cruising slowly with its flat underside close to the sediment. Four sensitive barbels hang beneath the snout ahead of the mouth, and these, together with electroreceptors and taste buds on the snout and lips, detect buried and hidden prey by touch, smell, and weak electric fields. When the fish locates something, its toothless mouth extends downward as a muscular tube and sucks the prey in along with sand and mud, which are sorted and expelled through the gills. This lets a sturgeon exploit worms, clams, insect larvae, and crustaceans that most fish cannot reach.

Why is sturgeon caviar so expensive?

Several factors compound. Only wild or farmed sturgeon produce true caviar, the salted unfertilised eggs, and a female must be raised or must survive in the wild for many years, often 10 to 20, before she carries a harvestable batch of roe. Wild stocks have collapsed, so legal wild caviar is now scarce and tightly regulated under CITES, and most caviar on the market comes from farms that tie up capital for a decade or more before the first harvest. Beluga caviar, from the largest and slowest-maturing species, is the rarest and most costly. The high price historically drove exactly the overfishing and poaching that wrecked the wild populations.

Can sturgeon populations recover?

Slowly, and only with sustained effort. Because sturgeon mature so late and spawn so infrequently, a depleted population takes decades to rebuild even under complete protection, and it cannot rebuild at all if dams still block the spawning rivers or if poaching continues. There are some encouraging cases. The lake sturgeon is recovering in parts of the Great Lakes basin under stocking and strict harvest limits, the white sturgeon persists where habitat allows, and Atlantic sturgeon numbers are slowly rising along the US coast after a fishing moratorium. But for species such as the Chinese sturgeon, whose main spawning grounds were cut off by dams, the wild future is very uncertain.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published September 10, 2026. Last updated September 10, 2026.

Quick facts

Scientific name: Acipenseridae
Diet: Bottom-living animals detected by touch and smell and vacuumed up through a toothless, tube-like protrusible mouth, including insect larvae, worms, crustaceans, molluscs, and small fish, with the largest species, the beluga, becoming a fish predator as an adult
A living fossil with a skeleton mostly of cartilage: Sturgeons appeared over 200 million years ago and have changed remarkably little, keeping an ancient set of features, a largely cartilaginous skeleton, a shark-like upturned tail, a spiral valve gut, and rows of bony plates called scutes instead of ordinary scales
Among the largest freshwater fish on Earth: The beluga sturgeon of the Caspian and Black seas has reliable historical records over 7 m and 1,500 kg, the white sturgeon of the North American Pacific coast exceeds 6 m, and the Chinese and kaluga sturgeons also reach several metres, making the family home to giants
They can live longer than a century: Sturgeons grow slowly and mature very late, with beluga females not spawning until 15 to 20 years old and lake sturgeon females sometimes not until 25, and individuals of several species have been aged at 60 to over 100 years, with one lake sturgeon estimated at around 125
They do not spawn every year: A mature female sturgeon spawns only once every two to seven years, migrating up a river to release millions of sticky eggs over gravel, so the number of fish actually breeding in any given year is a small fraction of the adult population
Their eggs are the original caviar: The unfertilised eggs of wild sturgeon, salted, are the classic caviar, and the enormous value of beluga, ossetra, and sevruga roe drove more than a century of overfishing and, from the 1990s, rampant poaching after the collapse of Soviet-era controls on the Caspian
The most threatened group of animals assessed by the IUCN: Of the 26 or so sturgeon and paddlefish species, around 85 to 90 per cent are listed as threatened and roughly two thirds as Critically Endangered, which the IUCN has described as making them the most endangered group of species on its Red List
Range: The Northern Hemisphere only, in the large rivers, lakes, and coastal seas of North America, Europe, and Asia, from the Gulf of Mexico and the North American Pacific coast across the rivers draining to the Black, Caspian, Azov, and Aral seas to the Amur, the Yangtze, and the rivers of Siberia, with many species migrating between fresh and salt water to spawn.
Conservation status: Critically Endangered ↓ ≈ Assessed at the family level as exceptionally threatened, with around two thirds of the roughly 26 species Critically Endangered and most of the rest Endangered or Vulnerable; wild populations of the commercially important species have fallen by 90 per cent or more, the Chinese sturgeon and several others may be functionally extinct in the wild, and the group survives in many rivers only through hatchery stocking, driven by overfishing for caviar, poaching, and dams that block spawning migrations in the wild